This invention relates to novel dispersant olefin copolymeric viscosity index improves having antioxidant properties on lubricants.
Additives which retard the tendency of a lubricating oil to thin as its temperature is raised from 100.degree. to 210.degree. F. are known as viscosity index improvers. Such improvers include ethylene-propylene copolymers. These are single function additives and to incorporate therein dispersancy characteristics the art has suggested grafting thereon polar nitrogen-containing monomers such as C-vinylpyridines and N-vinyl pyrrolidone (U.S. Pat. No. 4,170,561). These multipurpose additives, however, do not possess antioxidant properties when incorporated in lubricants. Ease of handling and cost dictate the use of multipurpose additives capable of imparting several desirable properties to lubricants. The present invention contributes to the art a trifunctional additive.